US 7215049 B2
A generator for a vehicle includes a stator having an armature coil, a rotor having a field coil and a voltage regulator having a surge absorbing capacitor element and a heat sink. The heat sink dissipates heat that is transmitted to the capacitor element, so that temperature of the capacitor element can be kept low enough to prevent deterioration of the capacitor element.
1. A generator for a vehicle comprising:
a stator including an armature coil,
a rotor including a field coil that induces ac power in the armature coil when excited,
a cooling fan, fixed to the rotor, for providing cooling air, and
a voltage regulator for regulating voltage of the ac power,
wherein said voltage regulator comprises a voltage control unit having a cooling fin for dissipating heat of said voltage control unit, a case, a surge absorbing capacitor element disposed in said case and a heat sink for dissipating heat that is transmitted to the capacitor element, and said heat sink is disposed outside said case separately from said cooling fin of said voltage control unit to be in thermal contact with a portion of said capacitor element and exposed to cooling air taken by the cooling fan.
2. The generator as claimed in
wherein said portion of said capacitor element comprises a capacitor terminal; and
said heat sink is disposed adjacent to one of the generator side terminal and the capacitor terminal.
3. The generator as claimed in
4. The generator as claimed in
5. The generator as claimed in
6. The generator as claimed in
The present application is based on and claims priority from Japanese Patent Application 2004-44396, filed Feb. 20, 2004, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a generator to be mounted in a vehicle and, more particularly, a voltage regulator with a surge absorbing capacitor element of such a generator.
2. Description of the Related Art
Usually, a generator mounted in a vehicle is composed of a stator core in which an armature coil is mounted, an engine-driven rotor in which a field coil is mounted, a rectifying unit which converts ac power generated by the armature coil to dc power, a voltage regulator which regulates output voltage of the generator, etc.
Such a regulator usually adopts a duty-ratio control system to control field current to be supplied to the field coil. In such a duty-ratio control system, electric surges are sometimes generated during switching operation. Such electric surges may cause harsh noise of audio devices and severe malfunction of other electronically controlled devices. In order to suppress such electric surges, a surge absorbing capacitor element has been introduced into the generator as disclosed in JP-A-2000-209824 or U.S. Pat. No. 6,236,557 B1, a counterpart of the former.
However, such a capacitor element is usually accommodated in a voltage regulator case, which is disposed near the rectifier unit. Therefore, the capacitor element is exposed to high temperature of the rectifier unit caused by switching and rectifying operation. In addition, the capacitor element is indirectly heated by the armature coil and the field coil in operation.
The capacitor element is mainly composed of an aluminum deposited polyester film, which may deteriorate if exposed to high temperature for a long time period. Although there is an idea of replacing the polyester film by a more heat-resistive film such as a polyphenilene sulfide film, this is too expensive.
In view of the above described problem, an object of the present invention is to provide a noise free and reliable generator for a vehicle that does not use an expensive noise suppressing capacitor.
Another object of the invention is to provide a noise-free voltage regulator equipped with a inexpensive heat resistive capacitor element.
According to a feature of the invention, a generator for a vehicle includes a stator having an armature coil, a rotor having a field coil that induces ac power in the armature coil when excited and a voltage regulator for regulating voltage of the ac power, wherein the voltage regulator comprises a surge absorbing capacitor element and a heat sink for dissipating heat that is transmitted to the capacitor element.
In the above described generator: the heat sink is disposed adjacent to a generator terminal or a terminal of the capacitor element; the heat sink may be integrated with the generator terminal or the terminal of the capacitor element; the capacitor element and the heat sink may be disposed in the case and covered with filling material; the voltage regulator may be disposed in the case together with the capacitor element and the heat sink; and the case may have a capacitor chamber for accommodating the capacitor element and a voltage regulator chamber for accommodating the voltage regulator.
Other objects, features and characteristics of the present invention as well as the functions of related parts of the present invention will become clear from a study of the following detailed description, the appended claims and the drawings. In the drawings:
A generator for a vehicle according to the first embodiment of the invention will be described with reference to
As shown in
The stator 3 and the rotor 5 are housed in a housing 13 that is composed of a front frame 11 and a rear frame 12. The stator 3 has a cylindrical body, which is fitted to the inside cylindrical wall of the housing 13, and the rotor 5 is disposed inside the stator 3 at a suitable air gap. The stator 3 has a plurality of axially extending slots to accommodate the armature coil 2 so as to form a three-phase stator winding.
The rotor 5 has a plurality of claw-shaped pole cores 14 and the field coil 4. The field coil 4 is wound around a rotary shaft 16 that is supported by a pair of bearings 15. One of the fans 17 is fixed to one axial end of the pole cores 14, and the other fan 17 is fixed to the other axial end of the pole cores 14. An end of the rotary shaft 16 projects from one axial end of the housing 13 to carry a pulley 21, and the other end carries a pair of slip rings 23, on which a pair of brushes is disposed to slide thereon. The rectifier unit 6 and the voltage regulator 7 are disposed at the other axial end of the housing 13 and covered by a rear cover 24.
The rear cover 24 is fixed to the housing 13 by a bolt 25 and a nut 26.
As shown in
As shown in
The regulator case 34 also has a capacitor element chamber 51. The capacitor element 32 has a cylindrical main body 52, a high voltage side terminal 53 that extends from one longitudinal end of the main body 52 and a low voltage side terminal 54 that extends from the other end in parallel to the former. The main body 52 of the capacitor element 32 is accommodated in the capacitor element chamber 51 and covered by filling material 55 to be completely buried therein. Both high voltage side and low voltage side terminals 53, 54 project from the filling material 55 into the rear cover 24, extend toward radially outer sides of the generator 1 and electrically connect to generator side terminals 56 that extend from the regulator case 34.
As shown in
As shown in
A voltage regulator according to the second embodiment of the invention will be described with reference to
As shown in
A voltage regulator according to the third embodiment of the invention will be described with reference to
As shown in
As a variation: the capacitor element 32 may be accommodated in a case separate from the regulator case; the heat sink 33 may be fixed to separate members projecting from the main body 52; or a pair of the heat sinks 33 may be replaced by a single heat sink 33.
In the foregoing description of the present invention, the invention has been disclosed with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific embodiments of the present invention without departing from the scope of the invention as set forth in the appended claims. Accordingly, the description of the present invention is to be regarded in an illustrative, rather than a restrictive, sense.